boundless; but that to assign satisfactory reasons for many mechanical processes required a general knowledge of that science. I have therefore borrowed a MS. copy of Dr. Black's Lectures. I have bought his 'Experiments on Magnesia and Quick Lime,' and also Fourcroy's Lectures,, translated from the French by one Mr. Elliot, of Edinburgh. And I am determined to study the subject with unwearied attention until I attain some accurate knowledge of chemistry, which is of no less use in the practice of the arts than it is in that of medicine." Such persistence and perseverance could not but attain success, and the result is to be seen to-day in the lasting qualities, that have been the admiration of succeeding engineers, of the lime concretes in the canals and other structures built by Telford. Both Fairbairn and George Stephenson received their first training at a colliery at Newcastle. Later in life, when Fairbairn had become a man of world-wide reputation as an engineer, he was elected President of the Institute of Mechanical Engineers at a meeting held at Newcastle, the scene of his work as a boy, and in the course of his address he said that had it. not been for the opportunities for self-education that Newcastle offered, opportunities that we should think very small now, and the use of the library at North Shields, he believed he should not have been there to address them. "Being self-taught, but with some little ambition, and a determination to improve himself, he was now enabled to stand before them with some pretensions to mechanical knowledge, and the persuasion that he had been a useful contributor to practical science and objects connected with mechanical engineering."
But the methods and reasoning by which such men arrived at their practical designs could not be expected to coincide with the methods of the academic exponents of the principles of mechanics, and it is hardly surprising to find Todhunter, in his History of the Theory of Elasticity,
